Self-centering means for extension-tables.



W, H. NORTHALL.

SELF CENTERING MEANS FOR EXTENSION TABLES.

APPLICATION FILED MAY 22, 1915.

Patented 00K 24, 1916.

2 VSHEETSSHEET 1.

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W1 TNESSES;

W.- H. NORTHALL.

SELF CENTERING MEANS FOR EXTENSION TABLES.

APPUCATQN FILED MAY 22, I915. jlfifififiwfi. Patented Oct. 24,1916.

2 $HEETS-SHEET 2 W1 TNESS'ES:

m: "cums PETERS conrnom-umo. WASNINGYGN a c TH A WILLIAM H. NORTI-IALL, OF EVANSVILLE, INDIANA, ASSIGNOR OF ONE-HALF TO FREDERICK W. GOEDEKE, OF EVANSVILLE, INDIANA.

SELF-GENTERING MEANS FOR EXTENSION-TABLES.

Application filed May 22, 1915.

To all whom it may concern:

Be it known that 1, WILLIAM H. NORTH- ALL, a citizen of the United States, residing at Evansville, in the county of Vanderburg and State of Indiana, have invented a new and useful Self-Centering Means for Extension-Tables, of which the following is a specification.

This invention has reference to self-centering means for extension tables, and its object is to provide a self-centering device for the purpose which will be at all times positive in action, of simple and compact structure, and which will permit a greater separation of the table top sections than has heretofore been accomplished.

In accordance with the present invention the extension table is provided with a separable top which may be collapsed to a minimum length and extended to a maximum length with the intervening space filled by extra leaves or otherwise and the two table; top sections are joined by interconnecting means so coacting that on applying a force to one section of the table top the other section will move away from the first section or toward it in accordance with the direction of the applied force.

The structure provided by the invention comprises rack bars attached to the respective table top sections and movable one along the other in close relation and for compactness of structure the rack bars are made flat and superposed with the rack teeth formed on the corresponding long edges of the two bars, so that both sets of rack teeth are directed toward the same side of the table. The rack bars are connected by a train of intermeshing gearing comprising terminal gear wheels and interconnecting idlers with the terminal gear wheels engaging the respective racks, whereby the rack bars are constrained to move in opposite directions and their free ends may be moved so as to be separated by a distance somewhat less than the distance between the engaging portions of the terminal members of the gear train, thus permitting with a certain length of rack bars a separation of the table top sections to a greater extent than heretofore.

The invention likewise includes a locking means whereby the table top sections may be locked together against movement toward or from each other at any polnt from Specification of Letters Patent.

Patented Get. 24, 1916.

Serial No. 29,834.

the closed to the open position of the table, wherefore the table is adaptable to the use of filling-in leaves irrespective of variations in the widths of the latter.

The invention will be best understood from a consideration of the following detailed description, taken in connection with the accompanying drawings forming part of this specification, with'the further understanding that while the drawings show a practical form of the invention, the latter is not confined to any strict conformity with the showing of the drawings but may be changed and modified so long as such changes and modifications mark no material departure from the salient features of the invention.

In the drawings :Figure 1 is a plan view of a table top embodying the present invention, the figure showing the table top extended and with the filling-in leaves omitted to expose certain parts of the mechanism to view. Fig. 2 is a section on the line 22 of Fig. 1. Fig. 3 is a plan view of the inter connecting gearing with the top of the casing thereof removed and certain parts projecting through the top of the casing shown in cross-section. Fig. at is a section 011 the line l4 of Fig. 1, but drawn on a larger scale and showing the rack bars in the position assumed when the table top sections are in closer approach than shown in Fig. 1. F i g 5 is a section on the line 55 of Fig. 3. Fig. 6 is an inverted plan view of the actuating member of the lock structure. Fig 7 is a horizontal section through the locking portion of the lock structure. Fig. 8 is a section on the line 88 of Fig. 7. Fig. 9 is a section on the line 99 of Fig. 6.

Referring to the drawings, there is shown a pedestal 1 which may be taken as indicative of any suitable support for a table top, most extension tables being of the pedestal type, but it will be understood that the invention is not of necessity limited to pedestal tables. Fast to the top of the pedestal are spider arms 2, as is customary, and these spider arms are connected at the outer ends by cross bars 3 extending laterally of the direction of extension of the table top.

The spider carries slides 4: in turn carrying table top sections 5, 6, respectively. Since neither the slides nor the table top sections form part of the present invention in their particular structure, they are neither shown nor described in detail, and may be considered as indicative of any sultable type of slide and table top sections.

In the drawings the sections 5 and (S are indicated as of a customary semi-circular shape, so that when the table is closed the table top is round, or may even be some-' What oblong, but these are features which do not enter into the present invention and the table top may be of any other desired configuration.

The'proportions chosen are usually such that the table when closed will be about half the length of the table when extended. It is quite common to provide a table which when closed will measure four feet across, while with the present invention such atable mayibe readily extended to'eight feet, but it will be understood that such particular proportions are not at all obligatory.

Fastened to the respective table tops on the under sides thereof and in the diameter of separation are brackets 7, 8. The bracket 7 has fast thereto one end of a rack bar 9 and the bracket 8 has fast thereto one end of a rack bar 10. These rack bars may be substantially identical in form and are shown as elongated, flat and relatively thin strips each formed with rack teeth 11, 12, respectively, along one long edge. The rack bars are each of such length that when the table top is fully extended they do not meet at the inner ends, butmay be separated by a considerable distance determined by the presence of certain structures to be described. Of course, the rack bars may be made longer than stated, but such additional length is unnecessary.

.The rack bar 9 is so disposed as to move over the rack bar 10 immediately above the latter; that is, it is in superposed relation thereto,while the teeth 11 and 12 of the two racks bars are directed toward the same side of the table since the 'ack bars are substantially iorizontal in the installed position both as regards their length and breadth and one need be located above the other only suliiciently to provide suitable clearance in order that the rack bars in moving in superposed relation do not come into end to end contact. 7

Fast at the ends to the respective cross bars 3 is a base plate 13 located in part in under-riding relation to the rack bars. Secured to the base plate 13 is a cover plate 1% having angle ears 15 at the ends, whereby the cover and base plate may be fastened together and to the strips? by screws 16 or otherwise with the main portion of the cover plate inupstanding spaced relation to the'base plate. Near one end the base plate 13 has struck up from it an upstanding V transverse ridge 17 which at one pointhas a cut away portion 18 for a purpose which will presently appear.

Fast to the ridge 17 near one end thereof and in central relation thereto is a stud 19 secured to the ridge by riveting or otherwise, and this stud is also carried through the corresponding portion of the cover 14: to which the stud may also be riveted. Mounted on the stud 19 between the ridge 17 and cover 14: is a gear wheel 20 having gear teeth 21 flanked on opposite sides by annular radial flanges .22.

At appropriate points the base plate 13 has struck up bosses 23, 24, 25. Rising from the boss 23 and secured thereto by riveting or otherwise is a stud 26 of a length to pass through the cover plate 1% to which the stud may be secured by riveting or otherwise. Mounted on the stud 26 between the boss 23 and plate 14 is a gear wheel 27 meshing with the gear wheel 20 between the flanges 22 and another gear wheel 28 connected to and spaced from the gear wheel 27 by a hub 29, so that the gear wheels 27 and 28 are effectively integral whether actually so or not.

The gear wheel 28 is at a lower level than the gear wheel 27 and at a cmrespondingly lower level than the gear wheel 20. Meshing with the gear wheel 28 is another gear wheel 30 carried by a stud 31 rising from and secured to the boss 24. The gear wheel 30 is in mesh with another gear wheel 32 having its teeth flanked by flanges 33 and the gear wheel 32 is mounted on a stud 8i. rising from the boss 25 and secured thereby by riveting or otherwise.

The arrangement of the gear wheels is such that the gear wheels 20 and 27 are at the same level and in mesh one with the other, while the gear wheels 28, 30 and 32 are on a lower level and in mesh one with the other. The studs 26 and 31 are displaced to one side 01"- a plane passing through the studs 19 and 3%. The rack bar 9 is in the particular showing of the drawings higher than the rack bar 10, and is so located with reference to the gear wheels that it extends over the base plate 13 in position to mesh with the gear wheel 30, but is too high to engage the gear wheel 32 and the gear wheel 27 is displaced to one side of the path of the rack bar 9. The rack bar 10 is in the particular showing of the drawings lower than the rack bar 9 and in underriding relation thereto and extends over the base plate 13 on a level and in mesh with the gear wheel 32, but is too low to engage the gear wheel 20, and its path of movement is to one side of the gear wheels 28 and 30. The cut away portion 18 is provided for the passage of the. rack bar 10 without interference from the ridge or ledge 17 The toothed edges of the rack bars engage the respective gear wheels 20 and 32 between their respective flanges 22 and 33, thereby confining the portions of the rack bars engaging the gear wheels against up and down movement. Opposite the gear wheel 20 and in position to engage the corresponding opposite edge of the rack bar 9 is a grooved guide roller 35 mounted on a stud 36 rising from the ridge 7 with the groove of the roller entered by the edge of the rack bar. The rack bar 10 is similarly engaged by another grooved roller 37 mounted on a stuc 38 rising from the base plate 13 opposite and in spaced relation to the gear wheel 32. The flanged gear wheels and 32 with the respective flanged rollers 35 and 37 eflectively hold the rack bars to the gear wheels against possibility of escape therefrom except by running off lengthwise from these gear wheels, which latter condition is prevented by the usual stop means limiting the separating movement of the table top sections.

The engaging gear wheels 20 and 32 constitute the terminal gear wheels of a series or train of gear wheels elongated in the direction of travel of table top sections. Since the rack bars move oppositely the gear wheels 20 and 32 likewise rotate oppositely and in order that the table top sections in their movements shall be properly centered the gear wheels 20 and 32 are constrained to move synchronously although in opposite directions by the interconnecting idler gear wheels 27 28 and 3,0. The gear wheels 27 and 28 are in ei tect a single gear wheel and might be made as one gear wheel of extra thickness to compensate for the diilerent levels of rack bars. Since the gear wheels 20. and 32 must rotate oppositely and since for the purposes of the present invention these gear wheels are separated and do not inter-mesh, the connecting idlers are either two in number or some multiple of two.

The purpose of separating the rack engaging gear wheels by the interposition of other direction-changing gear wheels is to permit the free ends of the rack bars, that is, those ends remote from the respective table tops, to move past each other, so as to become actually separated, and this permits a separation of the table top sections to a greater extent than heretofore without any increase in the length of the rack bars, and it is quite possible to provide for a greater separation of the table top sections than has heretofore been deemed feasible, and this without any complication of mechanism and without in any affecting the proper centering action of the centering mechanism.

The self-centering connections described are very compact and respond so readily to forces applied to open or close the table that it becomes necessary to provide a locking means holding the table top sections against movement toward or from each other. A simple form of locking structure is shown in the drawings. Fast to the two cross strips 3 to one side of the longitudinal center line or the table so as to be out of interfering relation with the self-centering devices are brackets 39 which may be simple angle brackets, each with an upstanding flange. Extending through the upstanding flanges of the two brackets is a rod 40 held against longitudinal movement in the brackets by any suitable means, such as by pins 41 or otherwise.

Fast to one of the rack bars, say, the rack bar 9, is a laterally extended housing 42 having a side extension 43 by which the housing is secured to the rack bar 9 so as to offstand laterally therefrom. The housing 42 has side wings 44, 45 in spaced parallel relation and traversed by the rod 40, the wings having perforations for the purpose. Mounted on therod 40 between the wings 44 and is a rockable gripper block 46 traversed by the rod 40 near one end of the block. The passage through the block 46 traversed by the rod 40 is indicated at 47 as of slightly greater diameter than the rod, so that the block may rock on the rod to bring diagonally opposite portions of the walls of the passage 47 into engagement with the rod, thereby firmly gripping the rod, and thus fastening the rack bar 9 to the rod by way of the housing 42. When the block 46 is in substantially parallel relation with the wing 45 against which it is normally pressed by a spring 48 on the rod 40 and bearing against the wing 44, the block 46 is relatively loose upon the rod 40 and the housing 42 with the parts to which it is. attached may be readily moved lengthwise of the rod 40 in either direction.

The block 46 at the end remote from the passage 47 is formed with ears 49 between which is pivoted one end of a rod or strip 50, which is long enough to have its other end close to the outer edge of one of the tabl top sections, say, the section 5. Fast to the under face of the section 5 is a bracket 51 to which is pivoted a rock arm 52 having an expanded head 53 through which a rivet or other suitable pivoting means is extended and secured to the bracket 51. The bracket 51 is provided with a curved slot 55 concentric with the rivet 54 for the reception ojlf'a stop pin 56 fast to the head 53, thus limiting the extent of movement of the rock arm or handle 52. The rod 50 has the end remote from the block 46 connected to the head 52 by a pivot pin 57 in eccentric relation to the rivet or pivot 54.

The arrangement is such that the rod 50 may be swung across the center of oscillation of the handle 52 and when in the pastcenter position the pin 56 engages the corresponding end of the slot 55. This position of the parts is attained when the block 46 has been moved by the rod 50 into cramped relation with the rod 40, thus clamping the has block 46 to the rod 40 and thereby locking the parts together. When the handle 52 is so rocked as to carry the rod 50 to the other side of the center represented by the rivet 54 the expansion of the spring 48 then causes the release of the rod from the block 46 by moving the latter against the wing 45 where it is no longer in cramping relation to the rod 40.

Of course, the handle 52 may be placed wherever deemed most convenient and it is usually placed under one table top section in position to be readily reached by a person attempting to spread or close the table.

The lock device shown is of extremely simple character and very efi'ectivesince it automatically holds the locked position without any special fastening devices and Will lock the table in any position within its range of movement, so that the table may be tightly locked when in the closed position and may be accommodated to leaves of various widths.

What is claimed is 1. A self-centering means for extension tables comprising superposed rack bars with rack teeth on the same sides of the two bars, and reversing gearing in mesh with the teeth of the'respective rack bars to cause simultaneous movement 'of both bars in opposite directio-ns on the actuation of either bar.

2. A self-centering means for extension tables comprising superposed rack bars with the teeth of the racks on the same sides of the bars, and a train of intermeshing gearing connecting the rack bars for simultaneous movement in opposite directions, the terminal members of the train of gearing each engaging a respective rack bar and the intermediate members of the train of gearing being displaced out of the path of the rack bars and in number suflicient to cause the simultaneous reverse movements of the rack bars on the actuation of either rack bar.

3. A self-centering means for extension tables comprising elongated rack bars in face to face superposed relation with the teeth of one rack bar on the same side as the teeth of the other rack bar, and an intermediately located train of gearing with the terminal members each in mesh with a respective one of the rack bars and the intermediate members of the gear train comprising a plurality of gear wheels laterally displaced out of the path of the rack bars and in number suflicient to impart opposite rotation to the terminal gears of the train, whereby table top sections connected to the respective rack bars may be moved apart by a distance represented by the sum of the runs of the rack bars plus the spacing apart of the terminal members of the gear train. a

4. A self-centering means for extension tables comprising two oppositely movable rack bars in superposed relationwith the teeth of the rack bars on the same side thereof, a train of gearing having terminal gear wheels in out of line relation with intermediate gear wheels and in difl'erent planes to mesh with the respective rack bars, and the intermediate members of the train of gearing being displaced with relation to the terminal gears to be in out of mesh relation to the rack bars, a supporting plate for the gears having an extension in underriding relation to the rack bars and a top member carried by the supporting plate in overriding relation to the gears.

A self-centering means for extension tables comprising two oppositely movable rack bars in superposed relation with the teeth of the rack bars on the same sides thereof, a train of gearing having terminal gears wheels in out of line relation with intermediate gear wheels and in different planes to mesh with the respective rack bars, and the'intermediate members of the train of gearing being displaced with relation to the terminal gears to be in out of line relation with the rack bars, a support ing plate for the gears having an extension in underriding relation to the rack bars, and a top member carried by the supporting plate in overriding relation to the gears, the terminal members of the gearshaving flanges flanking the gear teeth and embracing the toothed edges of the rack bars, and flanged rollers on the base plate engaging the edges of the rack bars remote from their toothed edges and being located in opposed relation to the terminal members of the gear train.

6. The combination with an extension table having a basic portion and separable top sections, of centering means for the top sections comprising rack bars each fast at one end to a respective top section and movable one over the other in superposed paths, rack bars having rack teeth on corresponding long edges both directed toward one side of the table, and a train of interconnected gearing having terminal members spaced apart and connected by intermediate members of the train with said terminal members in mesh with respective rack bars to cause both bars to move simultaneously in opposite directions on the actuation of either bar.

7 The combination with an' extension table having a basic portion and separable top sections, of centering means for the top sections comprising rack bars each fast at one end to a respective top section and movable one over the other in superposed paths, said rack bars having rack teeth on corresponding long edges both directed toward one side of the table, a train of interconnected gearing having terminal members spaced apart and connected by intermediate members of the train with said terminal members in mesh with respective rack bars to cause both bars to move simultaneously in opposite directions on the actuation of either bar, and a lock for the table top sections comprising a guide member fast to the basic member of the table, a grip member carried by one of the rack bars and mounted on the guide member, and an actuating member connected to the grip member and carried by one of the table top sections.

8. The combination With a table comprisflopies of this patent may be obtained for five cents each, by addressing the Gommissioner of Patents.

the closed position or any degree of extension comprising an elongated rod mounted on the basic portion of the table a cramp or grip block mounted slidably on the rod and connected to one of the members of the cen tralizing structure, and an eccentrically mounted operating means for the cramp block carried by the same table top section to which the centralizing member carrying the cramp block is connected.

In testimony that I claim the foregoing as my own. I have hereto aiiixed my signature in the presence of two Witnesses.

WILLIAM H. NORTHALL.

Witnesses:

F. C. GORE, Mrs. WM. NORTI-IALL.

Washington, D. 0. 

